Evaluation of new polymeric sorbents with high specific surface areas using an on-line solid-phase extraction-liquid chromatographic system for the trace-level determination of polar pesticides

1996 ◽  
Vol 737 (1) ◽  
pp. 15-24 ◽  
Author(s):  
Sophie Guenu ◽  
Marie-Claire Hennion
Keyword(s):  
Solid Phase ◽  
Chromatographic System ◽  
Trace Level ◽  
Polar Pesticides ◽  
Surface Areas ◽  
Polymeric Sorbents ◽  
On Line ◽  
Specific Surface Areas ◽  
Liquid Chromatographic

Determination of Streptomycin and Dihydrostreptomycin in Animal Tissue by On-Line Sample Enrichment Liquid Chromatography

1994 ◽  
Vol 77 (2) ◽  
pp. 334-337 ◽  
Author(s):  
Geoff C Gerhardt ◽  
Craig D C Salisbury ◽  
James D MacNeil
Keyword(s):  
Solid Phase ◽  
Animal Tissue ◽  
Extraction Column ◽  
Chromatographic System ◽  
Perchloric Acid Solution ◽  
Sample Enrichment ◽  
On Line ◽  
Liquid Chromatographic ◽  
Line Sample

Abstract A method for the determination of streptomycin and dihydrostreptomycin in pork and bovine muscle and kidney was developed. Dilute perchloric acid solution is used to precipitate proteins and extract the analytes from the tissue. The extract is loaded onto a cation-exchange, solid-phase extraction column, and the drugs are eluted with pH 8 phosphate buffer. The eluant is chromatographed by using an on-line column enrichment liquid chromatographic system with postcolumn derivatiza-tion using 1,2-naphthoquinone-4-sulfonic acid and detection by fluorescence. The recoveries were 61.1% (coefficient of variation [CV], 7.3%) for streptomycin and 55.3% (CV, 8.2%) for dihydrostreptomycin. The detection limits were 10 ppb for streptomycin and 20 ppb for dihydrostreptomycin.

Determination of Ardacin in Various Silage Feed Diets by a Rapid Liquid Chromatographic Assay

1995 ◽  
Vol 78 (1) ◽  
pp. 16-21
Author(s):  
Sylvia V B Fagan ◽  
Connie Gombatz ◽  
Hafez Abdel-Kader ◽  
Govind Menon
Keyword(s):  
Mobile Phase ◽  
Solid Phase ◽  
Chromatographic System ◽  
Method Of Calculation ◽  
Feed Formulation ◽  
Sample Extract ◽  
Liquid Chromatographic ◽  
Solid Phase Extract ◽  
Cyano Column

Abstract A method is presented for the detection and quantitation of Ardacin in silage feed diets by liquid chromatography, using a cyano column and an acetonitrile–methanol water mobile phase modified with trifluoroacetic acid. This method includes comprehensive procedures for extracting Ardacin from various silage feed formulations, cleaning up the extracted sample by using solid-phase extractions, and analyzing the eluted solid-phase extract with a suitable liquid chromatographic system. Ardacin was extracted from the silage feed formulations with 50% acetonitrile and 50% 0.1 M KOH. The extract was cleaned up with a wide-pore butyl solidphase extraction cartridge. The sample extract was chromatographed and quantified at 220 nm, using an external method of calculation. Recoveries of the medicated silage feed formulation ranged from 72.1 ± 1.7% to 109.1 ± 2.4%, depending on the sites and types of formulation analyzed.

Fully Automated Solid-Phase Extraction Cleanup and On-Line Liquid Chromatographic Determination of Benzimidazole Fungicides in Fruit and Vegetables

1995 ◽  
Vol 78 (5) ◽  
pp. 1267-1274 ◽  
Author(s):  
Maurice Hiemstra ◽  
Jeannette A Joosten ◽  
Andre de Kok
Keyword(s):  
Solid Phase Extraction ◽  
Solid Phase ◽  
Monitoring Program ◽  
Citrus Fruit ◽  
Phase Extraction ◽  
Benzimidazole Fungicides ◽  
On Line ◽  
Liquid Chromatographic ◽  
Automated Solid Phase Extraction

Abstract A liquid chromatographic (LC) method using fully automated solid-phase extraction (SPE) sample cleanup and on-line LC analysis was developed for determination of the benzimidazole fungicides car-bendazim and thiabendazole in various crops. Preparation of food samples involved extraction with acetone followed by solvent partitioning with dichloromethane–petroleum ether to draw the analytes into the organic phase. The laborious liquid–liquid partitioning cleanup procedure described in the literature was replaced with a fast SPE cleanup using diol-bonded silica cartridges. Automation of the total procedure was achieved by using a commercially available SPE cleanup apparatus (ASPEC). The cleaned-up extract was injected on-line into an LC system with UV and fluorescence detection in tandem. Chromatographic separations were performed with a methanol–phosphate buffer mobile phase (pH = 7) and different polymeric stationary phases. The polymer-based columns performed better than silica-based columns in separating benzimidazole fungicides, and different columns were compared. Results of validation studies with fortified lettuce and citrus fruit are presented. Shewhart control charts of analytical results of control samples demonstrated good performance of the complete system. Sample throughput (extraction, automated SPE, and on-line LC analysis) was about 50 samples per 24 h. Residues of carbendazim and thiabendazole found during our pesticide residue monitoring program in 1992–1994 are reported.

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